The High-Voltage MOSFET is used in a wide variety of applications covering from power systems up to RF-IC. Compact models that describe the high-frequency behavior of the device are required to predict high-frequency operation and switching capabilities of these elements in HV state-of-the-art systems. In this paper, an RF model is presented and verified against extensive Y-parameter measurements, which were carried out on a long channel Lateral double-Diffusion MOS device. Assessment of the model with measurements confirms the validity of this approach.